Abstract Human immunodeficiency virus (HIV) primarily enters the host and initiates infection through mucosal tissues. Therefore, a vaccination strategy that can elicit cellular and humoral immune responses in mucosal tissues is urgently needed. However, there is currently no approved adjuvant that can achieve robust levels of both T-cell and antibody responses in mucosal tissues. Therefore, there is a critical need for an alternative, effective, and safe strategy for mucosal vaccination. Our long-range goal is to develop vaccine delivery systems that can elicit protective immunity against HIV-1. Our objective here is to engineer nanoparticles for mucosal delivery of HIV-1 antigens and investigate their impact on elicitation of systemic and mucosal immune responses. To that end, we have developed a new nanoparticle (NP) system that can elicit strong cytotoxic CD8+ T lymphocyte (CTL) responses with subunit protein antigens. We show that these new vaccine NPs promote antigen delivery to antigen-presenting cells in vivo, generate CTLs that disseminate to mucosal tissues, including cervicovaginal and gastrointestinal tracts, and protect animals against viral infection. We also show that NPs induce significantly higher antibody titers, lasting > 400 days in mice with greater avidity, durability, and breadth, compared with conventional adjuvants on the market (e.g. alum or Montanide). Based on these preliminary data, we propose to develop a new NP-based strategy for mucosal immunization against HIV-1. We will test our central hypothesis that NPs incorporated with T and B-cell HIV-1 immunogens will elicit concerted cellular and humoral immune responses in mucosal tissues. At the completion of the proposed studies, we will have identified a new vaccination technology that can induce mucosal T and B cell responses against HIV-1. These studies will accelerate HIV-1 vaccine development and advance our understanding of the impact of vaccine delivery systems on mucosal immunity.